Viperin, an interferon inducible, endoplasmic reticulum associated gene product, which is active against RNA viral infection. aquaculture farms. L. haematocheila which has become an economically important mugilid species in off shore aquaculture along the west coast of Korea. Even though interferon stimulated genes were suspected actions against VHSV, specific pathway or mechanisms has not discussed for red lip mullet yet. And also past studies have shown that viperin levels were boost with the presence of double stranded RNA (ds RNA).
In silico study of the mullet viperin, which is a protein contains 355 amino acids, was disclosed a SAM binding conserved domain containing CNYKCGFC sequence. Isoelectric point and the molecular weight were determined to be 7.46 and 40.66 kilo Daltons, respectively. Alignment analysis revealed that 83.5% similarity to Zebra fish (Danio rerio) viperin. Furthermore, phylogenetic analysis indicated that viperin has unique origin compared to other fish. When considering the tissue distribution, highest expression was revealed in blood, followed by brain. In blood of poly I.C injected samples, approximately 17-fold upregulation compared to the control of viperin was detected after 24 hours. However, non-viral immune stimuli, including, L. garvieae and LPS injected samples not showed any significant viperin expression.
These results agree with the ability of the viperin to express strongly with the presence of poly I: C. Tissue distribution pattern may reveal by the strengthening viperin expression in vital organs similar to brain may beneficial for the fish. Challenge experiment reveal capability of poly I:C to solely enhance the expression, thus with the presence of virus RNA may also leads to a strong expression of viperin. However, more studies may require to fully characterize this unique protein in fish.